Vestiges of the Natural History of Creation matters because it widened public discussion of development, transformation, and natural history before Darwin's own public case. It is important less as a final scientific account than as a revealing publication node in the prehistory of Darwinism and in the public reception of evolutionary ideas.
The book helps make the nineteenth-century sequence more legible by showing that Darwin entered an already active public conversation. Its importance lies in public reception and intellectual atmosphere as much as in any single scientific claim.
That makes Vestiges valuable as a precursor text: a way to see how themes of development, transformation, and natural history were already circulating before Darwin became the dominant reference point.